Patent Application
20220344598
The present invention relates to an organic electroluminescent; device having a high light emission efficiency.
Studies are being actively performed, for enhancing the light emission efficiency of an organic light emitting device, such as organic electroluminescent device (organic EL device). In particular, various studies are being performed for enhancing the light emission efficiency by devising the material used in the light emitting layer. Among the studies, there are studies relating to an organic electroluminescent device containing a host material and a guest material (i.e., a light emitting dopant), in which the device emits light through migration of excitation energy formed in the host material to the guest material.
Patent Documents 1 and 2 describe an organic electroluminescent device using a host material, a light emitting dopant, and an assist dopant, as materials of a light emitting layer. In the organic electroluminescent device, the assist dopant complements the migration of carrier in the light emitting layer, and for example, a hole transferring material, such as a phenylamine derivative, is used therefor in the case where the transfer of electrons is complemented, and an electron transferring material is used therefor in the case where the transfer of holes is complemented. Patent Documents 1 and 2 describe that the use of the assist dopant, increases the probability of the recombination of carrier, and enhances the light emission efficiency of the organic electroluminescent device.
Patent Document 3 describes an organic electroluminescent device using a first dopant that is formed of a material capable of converting triplet excitation energy to light emission and has a first energy gap, a second dopant that is formed of a material capable of converting triplet excitation energy to light emission and has a second energy gap that is larger than the first energy gap, and a host material that has a third energy gap that, is larger than the second energy gap, as materials of a light emitting layer, and describes an organic metal complex having iridium as a center metal, as an example of the first dopant and the second dopant. Patent Document 3 describes that the use of the combination of the two kinds of dopants and the host material enhances the light mission efficiency of the organic electroluminescent device, lowers the driving voltage, and enhances the light emission lifetime.
Patent Document 1: JP-A-2005-108726
Patent Document 2: JP-A-2005-108727
Patent Document 3: JP-A-2006-41395
However, the electroluminescent devices of Patent Documents 1 and 2 cannot sufficiently enhance the light emission efficiency due to the following reasons.
In an organic electroluminescent device using a host material and a light emitting dopant, when holes and electrons are injected to the light emitting layer thereof, the holes end the electrons are recombined mainly in the molecules of the host material to form excitation energy, and the host material is in a singlet excited state and a triplet excited state. The probabilities of the formation of the excitons in a singlet excited state (i.e., singlet excitons) and the excitons in a triplet excited state (i.e., triplet excitons) are statistically 25% for the singlet excitons and 75% for the triplet excitons.
In the case where the light emitting dopant is a perylene derivative, an oxadiazole derivative or an anthracene derivative us exemplified in the literatures, the energy of the singlet excitons Is transferred to the light emitting dopant and excites the light emitting dopant to a singlet excited state. The light emitting dopant thus excited to a singlet excited state emits fluorescent light on returning to the original ground state. On the other hand, the energy of the triplet excitons is not transferred to the light emitting dopant, and the triplet excitons return to the ground state without contributing to the light emission. Accordingly, the organic electroluminescent device wastes the energy of the triplet excitons, which occupy 75% of the entire excitons, even though the probability of the recombination of the carrier is enhanced with the assist dopant, and thus is limited in enhancement of the light emission efficiency.
The organic electroluminescent device of Patent Document 3 uses a material capable of converting the triplet excitation energy to light emission, such as an iridium organic metal complex, as the first dopant. It has been known that an iridium organic metal complex receives triplet excitation energy front a host material, due to the effect of the heavy metal, and in this system, it is considered that the first dopant receives energy of the host material and the second dopant in a triplet excited state and can convert the energy to light emission. However, as the triplet excited state has a long lifetime, deactivation of the energy may occur due to the saturation of the excited state and the interaction with the excitons in a triplet excited state, and the quantum efficiency of the phosphorescence is generally not high. Accordingly, the organic electroluminescent device of the literature, which utilizes mainly light emission from the triplet excitation energy (i.e., phosphorescence), is difficult to enhance the light emission efficiency.
In consideration of the problems off the related art, the present inventors have made earnest investigations for providing an organic electroluminescent device having a high light emission efficiency.
As a result of earnest investigations, the inventors have found that by using a delayed fluorescent material as a assist dopant, the delayed fluorescent material in a triplet excited state undergoes inverse intersystem crossing to a singlet excited state, and thus the triplet excitation energy can consequently be converted to fluorescence, thereby providing an organic electroluminescent device having a high light emission efficiency. Based on the knowledge, the inventors thus have provided the invention shown below as a measure for solving the problems.
ES1(A)>ES1(B)>ES1(C) (A)
wherein ES1(A) represents a lowest singlet excitation energy level of the first organic compound; ES1(B) represents a lowest singlet excitation energy level of the second organic compound; and ES1(C) represents a lowest singlet excitation energy level of the third organic compound.
ET1(A)>ET1(B) (B)
wherein ET1(A) represents a lowest triplet excitation energy level at 77 K of the first organic compound; and ET1(B) represents a lowest triplet excitation energy level at 77 K of the second organic compound.
The organic light emitting device of the invention uses the combination of the three kinds of organic compounds that satisfy the particular condition, and thus has a feature of a considerably high light emission efficiency. In particular, the invention enhances the light emission efficiency in the case where the third organic compound is a compound that, emits fluorescent light on returning from the lowest singlet excitation energy level to the ground energy level.
The contents of the invention will be described in detail below. The constitutional elements may be described below with reference to representative embodiments and specific examples of the invention, but the invention is not limited to the embodiments and the examples. In the description, a numerical range expressed with reference to the expressions, an upper limit or less and/or a lower limit or more, means a range that includes the upper limit and/or the lower limit. In the invention, the hydrogen atom that is present in the compound used in the invention is not particularly limited in isotope species, and for example, all the hydrogen atoms in the molecule may be 1H, and all or a part of them may be 2H (deuterium (D)).
The organic electroluminescent device of the invention has a structure containing an anode, a cathode, and an organic layer formed between the anode and the cathode. The organic layer includes at least a light emitting layer, and the organic electroluminescent device of the invention has a characteristic feature in the constitution of the light emitting layer. The constitution of the light emitting layer will be described later.
The organic layer may contain only a light emitting layer, or may contain one or more additional organic layers in addition to the light emitting layer. Examples of the additional organic layer include a hole transporting layer, a hole injection layer, an electron barrier layer, a hole barrier layer, an electron injection layer, an electron transporting layer, and an exciton barrier layer. The hole transporting layer may be a hole injection and transporting layer having a hole injection function, and the electron transporting layer may be an electron injection and transporting layer having an electron injection function. A specific structural example of the organic electroluminescent device is shown in
The members and the layers of the organic electroluminescent device will be described below.
In the light emitting layer, holes and electrons injected from the anode and the cathode respectively are recombined to form excitons, and then the layer emits light.
In the organic electroluminescent device of the invention, the light emitting layer contains the first organic compound, the second organic compound, and the third organic compound that satisfy the following expression (A), in which the second organic compound is a delayed fluorescent material, and the third organic compound is a light emitting material.
ES1(A)>ES1(B)>ES1(C) (A)
In the expression (A), ES1(A) represents the lowest singlet excitation energy level of the first organic compound; ES1(B) represents the lowest singlet excitation energy level of the second organic compound; and ES1(C) represents the lowest singlet excitation energy level of the third organic compound.
The delayed fluorescent material in the invention means an organic compound that is capable of being transferred to the triplet excited state and then undergoing inverse intersystem crossing to the singlet excited state, and emits fluorescent light on returning from the singlet excited state to the ground state. The light formed through the inverse intersystem crossing from the triplet excited state to the singlet excited state has a lifetime that is longer than normal fluorescent light (prompt fluorescent light) and phosphorescent light, and thus is observed as fluorescent light that is delayed therefrom. Accordingly, the fluorescent light of this type is referred to as delayed fluorescent light.
In the light emitting layer, the first to third organic compounds have the lowest singlet excitation energy levels ES1(A), ES1(B), and ES1(C) satisfying the expression (A), and the second organic compound is a delayed fluorescent material, whereby the excitation energy formed through recombination of holes and electrons injected to the light emitting layer is efficiently converted to fluorescent light to provide a high light emission efficiency. The mechanism thereof is considered as follows.
In the light emitting layer, when the excitation energy is formed through recombination of holes and electrons, the organic compounds contained in the light emitting layer are transferred from the ground state to the singlet excited state and the triplet exited state. The probabilities of the formation of the organic compounds in a singlet excited state (i.e., singlet excitons) and the organic compounds in a triplet excited state (i.e., triplet excitons) are statistically 25% far the singlet excitons and 75% for the triplet excitons. Among the excitons, the energy of the first organic compound and the second organic compound in the singlet excited state is transferred to the third organic compound, and the third organic compound in the ground state is transferred to the singlet excited state. The third organic compound thus in the singlet excited state emits fluorescent light on returning to the ground state.
In the organic electroluminescent device of the invention at this time, the second organic compound in the triplet exited state undergoes inverse intersystem crossing to the singlet excited state since the second organic compound is a delayed fluorescent material, and the singlet excitation energy due to the inverse intersystem crossing is also transferred to the third organic compound. Accordingly, the energy of the second organic compound in the triplet excited state, which has a large existence probability, also contributes indirectly to the light emission, and thus the light emission efficiency of the organic electroluminescent device is significantly enhanced as compared to an organic electroluminescent device having a constitution that does not contain the second organic compound in the light emitting layer.
In the organic electroluminescent device of the invention, the light emission occurs mainly from the third organic compound, and a part of the light emission may occur from the first organic compound and the second organic compound, or the light emission may partially occur therefrom. The light emission contains both fluorescent light and delayed fluorescent light.
In the organic electroluminescent device of the invention, the kinds and the combinations of the first organic compound, the second organic compound, and the third organic compound, as far as the second organic compound is a delayed fluorescent material, and the third organic compound is a light emitting material. The organic electroluminescent device of the invention preferably satisfies the following expression (B) from the standpoint that a further higher light emission efficiency may be achieved thereby.
ET1(A)>ET1(B) (B)
In the expression (B), ET1(A) represents the lowest triplet excitation energy level at 77 K of the first organic compound; and ET1(B) represents the lowest triplet excitation energy level at 77 K of the second organic compound. The relationship between the lowest triplet excitation energy level at 77 K of the second organic compound ET1(B) and the lowest triplet excitation energy level at 77 K of the third organic compound ET1(C) is not particularly limited, and may be selected to satisfy the expression, ET1(B)>ET1(C).
The invention will be described more specifically with reference to preferred examples below, but the scope of the invention is not construed as being limited to the following description based on the preferred examples.
The delayed fluorescent material used as the second organic compound is not particularly limited, and is preferably a thermal activation type delayed fluorescent material undergoing inverse intersystem crossing from the singlet excited state to the triplet excited state through absorption of heat energy. The thermal activation type delayed fluorescent material relatively easily undergoes inverse intersystem crossing from the singlet excited state to the triplet excited state through absorption, of heat that is formed by the device, and can make the triplet excitation energy thereof contribute to the light emission efficiently.
The delayed fluorescent material preferably has an energy difference ΔEst between the energy level ES1 in the lowest singlet excited state and the energy level ES1 in the lowest triplet excited state at 77 K of 0.3 eV or less, more preferably 0.2 eV or less, further preferably 0.1 eV or less, and still further preferably 0.08 eV or less. The delayed fluorescent material that has an energy difference ΔEst within the range relatively easily undergoes inverse intersystem crossing from the singlet excited state to the triplet excited state, and can make the triplet excitation energy thereof contribute to the light emission efficiently.
The delayed fluorescent material used as the second organic compound is not particularly limited, as far as the compound is capable of emitting delayed fluorescent light, and for example, a compound represented by the following general formula (1) may be preferably used.
wherein in the general formula (1), Ar1 to Ar3 each independently represent a substituted or unsubstituted aryl group, provided that at least one of Ar1 to Ar3 represents an aryl group substituted with a group represented by the following general formula (2):
wherein in the general formula (2), R1 to R8 each independently represent a hydrogen atom or a substituent; Z represents O, S, O═C, or Ar4-N; Ar4represents a substituted or unsubstituted aryl group, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, and R7 and R8 each may be bonded to each other to form a cyclic structure.
The aromatic ring constituting the aryl group represented by Ar1 to Ar3 in the general formula (1) may be a monocyclic ring or a condensed ring, and specific examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. The aryl group preferably has from 6 to 40 carbon atoms, more preferably from 6 to 20 carbon atoms, and further preferably from 6 to 14 carbon atoms. At least one of Ar1 to Ar3 represents an aryl group substituted with a group represented by the general formula (2). Two of Ar1 to Ar3 each may be an aryl group substituted with a group represented by the general formula (2), and three of them each may be an aryl group substituted with a group represented by the general formula (2). One aryl group may be substituted with two or more groups each represented by the general formula (2). For the descriptions and the preferred ranges of the substituent that is capable of being substituted on the aryl group represented by Ar1 to Ar3, reference may be made to the descriptions and the preferred ranges of the substituent represented by R1 to R8 described later.
In the general formula (2), R1 to R8 each independently represent a hydrogen atom or a substituent. All R1 to R8 may be hydrogen atoms. In the case where two or more thereof are substituents, the substituents may be the same as or different from each other. Examples of the substituent include a hydroxyl group, a halogen atom, a cyano group, an alkyl group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, an alkylthio group having from 1 to 20 carbon atoms, an alkyl-substituted amino group having from 1 to 20 carbon atoms, an aryl-substituted amino group having from 12 to 40 carbon atoms, an acyl group having from 2 to 20 carbon atoms, an aryl group having from 6 to 40 carbon atoms, a heteroaryl group having from 3 to 40 carbon atoms, a substituted or unsubstituted carbazolyl group having from 12 to 40 carbon atoms, an alkenyl group having from 2 to 10 carbon atoms, an alkynyl group having from 2 to 10 carbon atoms, an alkoxycarbonyl group having from 2 to 10 carbon atoms, an alkylsulfonyl group having from 1 to 10 carbon atoms, a haloalkyl group having from 1 to 10 carbon atoms, an amide group, an alkylamide group having from 2 to 10 carbon atoms, a trialkylsilyl group having from 3 to 20 carbon atoms, a trialkylsilylalkyl group having from 4 to 20 carbon atoms, a trialkylsilylalkenyl group having from 5 to 20 carbon atoms, a trialkylsilylalkynyl group having from 5 to 20 carbon atoms, and a nitro group. In these specific examples, the substituent that is capable of being further substituted with a substituent may be substituted. More preferred examples of the substituent include a halogen atom, a cyano group, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having from 3 to 40 carbon atoms, a substituted or unsubstituted dialkylamino group having from 2 to 10 carbon atoms, a substituted or unsubstituted diarylamino group having from 12 to 40 carbon atoms, and a substituted or unsubstituted carbazolyl group having from 12 to 40 carbon atoms. Further preferred examples of the substituent include a fluorine atom, a chlorine atom, a cyano group, a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having from 1 to 10 carbon atoms, a substituted or unsubstituted dialkylamino group having from 2 to 10 carbon atoms, a substituted or unsubstituted diarylamino group having from 12 to 40 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 15 carbon atoms, and a substituted or unsubstituted heteroaryl group having from 3 to 12 carbon atoms.
The alkyl group referred in the description herein may be linear, branched or cyclic, and more preferably has from 1 to 6 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a tert-butyl group, a pentyl group, a hexyl group, and an isopropyl group. The aryl group may be a monocyclic ring or a condensed ring, and specific examples thereof include a phenyl group and a naphthyl group. The alkoxy group may be linear, branched or cyclic, and more preferably has from 1 to 6 carbon atoms, and specific examples thereof include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a tert-butoxy group, a pentyloxy group, hexyloxy group, and an isopropoxy group. The two alkyl groups of the dialkylamino group may be the same as or different from each other, and are preferably the same as each other. The two alkyl groups of the dialkylamino group each Independently way be linear, branched or cyclic, and more preferably have front 1 to 6 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and an isopropyl group. The two alkyl groups of the dialkylamino group may be bonded to form a cyclic structure along with the nitrogen atom of the amino group. The aryl group that may be used as the substituent may be a monocyclic ring or a fused ring, and specific examples thereof include a phenyl group and a naphthyl group. The heteroaryl group may be a monocyclic ring or a fused ring, and specific examples thereof include a pyridyl group, a pyridazyl group, a pyrimidyl group, a triazinyl group, a triazolyl group, and a benzotriazolyl group. The heteroaryl group may be a group that is bonded through the hetero atom or a group that is bonded through the carbon atom constituting the heteroaryl ring. Two aryl groups of the diarylamino group each may be a monocyclic ring or a fused ring, and specific examples thereof include a phenyl group and a naphthyl group. Two aryl groups, of the diarylamino group may be bonded to each other to form a cyclic structure along with the nitrogen atom of the amino group, and examples thereof include a 9-carbazolyl group.
In the general formula (2), R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, and R7 and R8 each may be bonded to each other to form a cyclic structure. The cyclic structure may be an aromatic ring or an aliphatic ring, and may contain a heteroatom. The hetero atom referred herein is preferably selected from a group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of the cyclic structure formed include a benzene ring, a naphthalene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a pyrrole ring, an imidazole ring, a pyrazole ring, a triazole ring, an imidazoline ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, a cyclohexadiene ring, a cyclohexene ring, a cyclopentene ring, a cycloheptatriene ring, a cycloheptadiene ring, and a cycloheptene ring.
In the general formula (2), Z represents O, S, O═C, or Ar4-N, and Ar4 represents a substituted or unsubstituted aryl group. The aromatic ring constituting the aryl group represented by Ar4 may be a monocyclic ring or a condensed ring, and specific examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. The aryl group preferably has from 6 to 40 carbon atoms, more preferably from 6 to 20 carbon atoms, and further preferably from 6 to 14 carbon atoms. For the descriptions and the preferred ranges of the substituent that is capable of being substituted on the aryl group represented by Ar4, reference may be made to the descriptions and the preferred ranges of the substituent that may be represented by R1 to R8.
The group represented by the general formula (2) is preferably a group represented by the following general formula (3), a group represented by the following general formula (4), or a group represented by the following general formula (5).
In the general formulae (3) to (5), R1 to R8 each Independently represent a hydrogen atom or a substituent. For the descriptions and the preferred ranges of R1 to R8, reference may be made to the corresponding descriptions in the general formula (2). R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, and R7 and R8 may be bonded to each other to form a cyclic structure.
In the general formula (2), in the case where Z represents Ar4-N, the compound represented by the general formula (1) particularly encompasses the structure represented by the following general formula (6):
In the general formula (6), Ar2, Ar3, Ar2′, and Ar3′ each independently represent a substituted or unsubstituted aryl group; Ar5 and Ar5′ each independently represent a substituted or unsubstituted arylene group; and R1 to R8 each independently represent a hydrogen atom or a substituent, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, and R7 and R8 may be bonded to each other to form a cyclic structure.
For the descriptions and the preferred ranges of Ar2, Ar3, Ar2′, and Ar3′ in the general formula (6), reference may be made to the descriptions and the preferred ranges of Ar1 to Ar3 in the general formula (1). The aromatic ring constituting the arylene group represented by Ar5 and Ar5′ in the general formula (6) may be a monocyclic ring or a condensed ring, and specific examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. The arylene group preferably has from 6 to 40 carbon atoms, more preferably from 6 to 20 carbon atoms, and further preferably from 6 to 14 carbon atoms. For the descriptions and the preferred ranges of R1 to R8 in the general formula (6), reference may be made to the descriptions and the preferred ranges of R1 to R8 in the general formula (2).
In the compound represented by the general formula (6), the compound, in which Ar2 and Ar2′ are the same as each other, Ar3 and Ar3′ are the same as each other, and Ar5 and Ar5′ are the same as each other, has such an advantage that the compound may be easily synthesized.
The compound represented by the general formula (1) preferably has a structure represented by the following general formula (7):
In the general formula (7), at least one of R11 to R25 represents a group represented by the general formula (2); and the other thereof each independently represent a hydrogen atom or a substituent other than a substituent represented by the general formula (2).
In the general formula (7), at least one of R11 to R25 represents a group represented toy the general formula (2), and the number of the substituent represented by the general formula (2) is preferably from 1 to 9, and more preferably from 1 to 6, among R11 to R25. For example, the number of the substituent, may be selected from a range of from 1 to 3. The group represented by the general formula (2) may be bonded to each of the three benzene rings bonded to the 1,3,5-triazine ring, or may be only one or two benzene rings. Preferred examples thereof include a case where the three benzene rings each have from 0 to 3 of the substituent represented by the general formula (2), and more preferred examples thereof include a case where the three ten zone rings each have from 0 to 2 of the substituent represented by the general formula (2). For example, a case where the three benzene rings each have 0 or 1 of the substituent represented by the general formula (2) may be selected.
The substitution position of the group represented by the general formula (2) may be any one of R11 to R25, and the substitution position is preferably selected from R12 to R14, R17 to R19, and R22 to R24. Examples thereof include a case where from 0 to 2 of R12 to R14, from 0 to 2 of R17 to R19, and from 0 to 2 of R22 to R24 each represent the substituent represented by the general formula (2), and a case where 0 or 1 of R12 to R14, 0 or 1 of R17 to R19, and 0 or 1 of R22 to R24 each represent the substituent represented by the general formula (2).
In the case where any one of R11 to R25 is substituted by the substituent represented by the general formula (2), the substitution position, thereof is preferably R12 or R13. In the case where any two of R11 to R25 are substituted by the substituent represented by the general formula (2), the substitution positions thereof are preferably R12 and R14, or any one of R12 and R13 and any one of R17 and R18. In the case where any three of R11 to R25 are substituted by the substituent represented by the general formula (2), the substitution positions thereof are preferably R12, R14, and any one of R17 and R18, or any one of R12 and R13, any one of R17 and R18, and any one of R22 and R23.
Among R11 to R25, ones that do not represent the substituent represented by the general formula (2) each independently represent a hydrogen atom or a substituent other than a substituent represented by the general formula (2), and may be all hydrogen atoms. In the case where two or more of them are the substituents, the substituents may be different from each other. For the descriptions and the preferred ranges of the substituent that may be represented by R11 to R25, reference may be made to the descriptions and the preferred ranges of the substituent that way be represented by R1 to R8.
In the general formula (7), R11 and R12, R12 and R13, R13 and R14, R14 and R15, R16 and R17, R17 and R18, R18 and R19, R19 and R20, R21 and R22, R22 and R23, R23 and R24, and R24 and R25 each may be bonded to each other to form a cyclic structure. For the descriptions and the preferred ranges of the cyclic structure, reference may be made to the corresponding descriptions in the general formula (2).
The group represented by the general formula (2) contained In the general formula (7) is preferably a group having a structure represented by the general formula (3), a group having a structure represented by the general formula (4), or a group having a structure represented by the general formula (5).
The compound represented by the general formula (7) preferably has a symmetric molecular structure. For example, the compound preferably has a rotation symmetric structure with the center of the triazine ring as the axis. In this case, in the general formula (7), R11, R16, and R21 are the same as each other, R12, R17, and R22 are the same as each other, R13, R18, and R23 are the same as each other, R14, R19, and R24 are the same as each other, and R15, R20, and R25 are the same as each other. Examples of the compound in this case include the compound, in which R13, R18 and R23 are the groups represented by the general formula (2), and the others are hydrogen atoms.
In the general formula (2), in the case where Z represents Ar4-N, the compound represented by the general formula (7) particularly encompasses the structure represented by the following general formula (8):
In the general formula (8), R1 to R8, R11, R12, R14 to R25, R11′, R12′, and R14′ are R25′ each independently represent a hydrogen atom or a substituent. For the descriptions and the preferred ranges of R1 to R8 in the general formula (8), reference may be made to the descriptions and the preferred ranges of R1 to R8 in the general formula (2). For the descriptions and the preferred ranges of R11, R12, R14 to R25, R11′, R12′, and R14′ are R25′ in the general formula (8), reference may be made to the descriptions and the preferred ranges of R11 to R25 in the general formula (7). In the general formula (8), R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, R7 and R8, R11 and R12, R14 and R15, R16 and R17, R17 and R18, R18 and R19, R19 and R20, R21 and R22, R22 and R23, R23 and R24, R24 and R25, R11′ and R12′, R14′ and R15′, R16′ and R17′, R17′ and R18′, R18′ and R19′, R19′ and R20′, R21′ and R22′, R22′ and R23′, R23′ and R24′, and R24′ and R25′ each may be bended to each other to form a cyclic structure. For the descriptions and the preferred ranges of the cyclic structure, reference may be made to the corresponding descriptions in the general formula (2).
Specific examples of the compound represented by the general formula (1) shown below. However, the compound represented by the general formula (1) capable of being used in the invention is not construed as being limited to the specific examples.
A compound represented by the following general formula (9) may be preferably used as the delayed fluorescent material used as the second organic compound.
In the general formula (9), X represents an oxygen atom, a sulfur atom, or a nitrogen atom (in which a hydrogen atom or a substituent is bonded to the nitrogen atom, and the substituent is preferably an alkyl group having from 1 to 10 carbon atoms or an aryl group having from 6 to 14 aryl group); and R1 to R8 each independently represent a hydrogen atom or a substituent, provided that at least one of R1 to R8 each independently represent a group represented by any one of the general formulae (10) to (14). X may be an oxygen atom or a sulfur atom, and is preferably an oxygen atom.
The number, of the group represented by any one of the general formulae (10) to (14) among R1 to R8 may be only 1 or 2 or more, and is preferably from 1 to 4, and more preferably 1 or 2. In the case where plural groups each represented by any one of the general formulae (10) to (14) are present in the general formula (9), the groups may be the same as or different from each other.
In the case where only one of R1 to R8 is the group represented by any one of the general formulae (10) to (14), R2 or R3 is preferably the group represented by any one of the general formulae (10) to (14), and R3 is more preferably the group represented by any one of the general formulae (10) to (14).
In the case where two or more of the R1 to R8 each are the group represented by any one of the general formulae (10) to (14), at least one of R1 to R4 and at least one of R5 to R8 each are preferably the group represented by any one of the general formulae (10) to (14). In this case, the groups represented by any one of the general formulae (10) to (14) are preferably from 1 to 3 of R1 to R4 and from 1 to 3 of R5 to R8, and more preferably 1 or 2 of R1 to R4 and 1 or 2 of R5 to R8. The number of the group represented by any one of the general formulae (10) to (14) among R1 to R4 and the number of the group represented by any one of the general formulae (10) to (14) among R5 to R6 may be the same as or different from each other, and are preferably the same as each other. In R1 to R4, it is preferred that at least one of R2 to R4 is the group represented by any one of the general formulae (10) to (14), and it is more preferred that at least R3 is the group represented by any one of the general formulae (10) to (14). In R5 to R6, it is preferred that at least one of R5 to R7 is the group represented by any one of the general formulae (10) to (14), and it is more preferred that at least R6 is the group represented by any one of the general formulae (10) to (14). Preferred examples of the compound include the compound represented by the general formula (9), in which R3 and R6 each represent the group represented by any one of the general formulae (10) to (14), the compound represented by the general formula (9), in which R2 and R7 each represent the group represented by any one of the general formulae (10) to (14), and the compound represented by the general formula (9), in which R2, R3, R6 and R7 each represent the group represented by any one of the general formulae (10) to (14), and more preferred examples of the compound include the compound represented by the general formula (9), in which R3 and R6 each represent the group represented by any one of the general formulae (10) to (14). The plural groups each represented by any one of the general formulae (10) to (14) present in the general formula (9) may be the same as or different from each other, and are preferably the same as each other. The compound represented by the general formula (9) preferably has a symmetric structure. Specifically, R1 and R8, R2 and R7, R3 and R6, and R4 and R5 each are preferably the same as each other.
In the compound represented by the general formula (9), both R3 and R6 are preferably the groups represented by any one of the general formulae (10) to (14). Preferred examples of the compound include a compound represented by the general formula (9), in which at least one of R3 and R6 is the groups represented by any one of the general formulae (10) to (14).
In the general formulae (10) to (14), L20, L30, L40, L50 and L60 each independently represent a single bond or a divalent linking group; and R21 to R28, R31 to R38, R3a, R3b, R41 to R48, R4a, R51 to R58, and R61 to R68 each independently represent a hydrogen atom or a substituent.
L20, L30, L40, L50 and L60 each may represent a single bond or a divalent linking group, and preferably represent a single bond. In the case where at least one of R1 to R8 in the general formula (9) each represent the group represented by any one of the general formulae (10) to (14), wherein L20, L30, L40, L50 and L60 each represent a linking group, the number of the linking group present in the general formula (9) may be only 1 or may be 2 or more. In the case where the general formula (9) contains plural linking groups, the linking groups may be the same as or different from each other. Examples of the divalent linking group that may be represented by L20, L30, L40, L50 and L60 include an alkenylene group, an alkynylene group, an arylene group, a thiophendiyl group, and a linking group formed of a combination of these groups. The alkylene group and the alkenylene group each preferably have from 2 to 10 carbon atoms, more preferably from 2 to 6 carbon atoms, and further preferably from 2 to 4 carbon atoms. The arylene group preferably has from 6 to 10 carbon atoms, and more preferably 6 carbon atoms, and a p-phenylene group is further preferred. Examples of the thiophendiyl group include a 3,4-thiophendiyl group and 2,5-thiophendiyl group. Preferred examples of the linking group include a linking group represented by the general formula —(CRa═CRb)n—. In the general formula, Ra and Rb each independently represent a hydrogen atom or an alkyl group. The alkyl group preferably has from 1 to 6 carbon atoms, and more preferably from 1 to 3 carbon atoms. n is preferably from 1 to 6, more preferably from 1 to 3, and further preferably 1 or 2. Examples thereof include —CH═CH— and —(CH═CH) 2—.
The number of a substituent in the general formulae (10) to (14) is not particularly limited. In each of the general formulae (10) to (14), all R21 to R28, R31 to R38, R3a, R3b, R41 to R48, R4a, R51 to R58, and R61 to R68 each may be unsubstituted (i.e., a hydrogen atom), it is preferred that at least one of R21 to R28, R31 to R38, R41 to R48, R51 to R58, and R61 to R68 each represent a substituent, and it is more preferred that at least one of R23, R26, R33, R36, R43, R46, R53, R56, R63 and R66 each represents a substituent. In the case where the general formulae (10) to (14) contain plural substituents, the substituents may be the same as or different from each other.
Examples of the substituent that may be represented by R21 to R28, R31 to R38, R3a, R3b, R41 to R48, R4a, R51 to R58, and R61 to R68 and the substituent that may be represented by R1 to R8 include a hydroxyl group, a halogen atom, a cyano group, an alkyl group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, an alkylthio group having from 1 to 20 carbon atoms, an alkyl-substituted amino group having from 1 to 20 carbon atoms, an acyl group having from 2 to 20 carbon atoms, an aryl group having from 6 to 40 carbon atoms, a heteroaryl group having from 3 to 40 carbon atoms, an alkenyl group having from 2 to 10 carbon atoms, an alkynyl group having from 2 to 10 carbon atoms, an aIkoxycarbonyl group having from 2 to 10 carbon atoms, an alkylsulfonyl group having from 1 to 10 carbon atoms, a haloalkyl group having from 1 to 10 carbon atoms, an amide group, an alkylamide group having from 2 to 10 carbon atoms, a trialkyIsilyl group having from 3 to 20 carbon atoms, a trialkylsilylalkyl group having from 4 to 20 carbon atoms, a trialkylsilylalkenyl group having from 5 to 20 carbon atoms, a trialkylsilylalkynyl group having from 5 to 20 carbon atoms, and a nitro group. In these specific examples, the substituent that is capable of being further substituted with a substituent may be substituted. More preferred examples of the substituent include a halogen atom, a cyano group, a substituted or unsubstituted alkyl group having from 1 to 20 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having from 3 to 40 carbon atoms, and a dialkyl-substituted amino group having from 1 to 20 carbon atoms. Further preferred examples of the substituent include a fluorine atom, a chlorine atom, a cyano group, a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having from 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having from 6 to 15 carbon atoms, and a substituted or unsubstituted heteroaryl group having from 3 to 12 carbon atoms.
At least one of R23, R26, R33, R36, R43, R46, R53, R56, R63 and R66 each preferably Independently represent the group represented by any one of the general formulae (10) to (14).
R1 and R2, R2 and R2, R3 and R4, R5 and R6, R6 and R7, and R7 and R8, R21 and R22, R22 and R23, R23 and R24, R24 and R25, R25 and R26, R26 and R27, R27 and R28, R31 and R32, R32 and R33, R33 and R34, R35 and R36, R36 and R37, R37 and R38, R3a and R3b, R41 and R42, R42 and R43, R43 and R44, R45 and R46, R46 and R47, R47 and R48, R51 and R52, R52 and R53, R53 and R54, R55 and R56, R56 and R57, R57 and R58, R61 and R62, R62 and R63, R63 and R64, R64 and R65, R66 and R67, and R67 and R68 each may be bended to each other to form a cyclic structure. The cyclic structure may be an aromatic ring or an aliphatic ring, and may contain a hetero atom, and the cyclic structure may be a condensed ring containing two or more rings. The hetero atom referred herein Is preferably selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom. Examples of the cyclic structure formed include a benzene ring, a naphthalene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a pyrrole ring, an imidazole ring, a pyrazole ring, a triazole ring, an imidazoline ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, a cyclohexadieme ring, a cyclohexene ring, a cyclopentene ring, a cycloheptatriene ring, a cycloheptadiene ring, and a cycloheptene ring.
Specific examples of the compound represented by the general formula (9) shown below. However, the compound represented by the general formula (9) capable of being used in the invention is not construed as being limited to the specific examples.
As the second organic compound, the following light emitting material capable of emitting delayed fluorescent light is also preferably used.
Preferred examples of the light emitting material include compounds represented by the following general formula (101). The entire description of WO 2013/154064 including the paragraphs 0008 to 0048 and 0095 to 0133 is incorporated herein by reference.
wherein in the general formula (101), at least one of R1 to R5 represents a cyano group, at least one of R1 to R5 represents a group represented by the following general formula (111), and the balance of R1 to R5 each represent a hydrogen atom or a substituent,
wherein in the general formula (111), R21 to R28 each independently represent a hydrogen atom or a substituent, provided that at least one of the following conditions (A) and (B) is satisfied:
In the general formula (101), at least one of R1 to R5 preferably represents a group represented by any one of the following general formulae (112) to (115).
wherein in the general formula (112), R31 to R38 each independently represent a hydrogen atom or a substituent,
wherein in the general formula (113), R41 to R46 each independently represent a hydrogen atom or a substituent,
wherein in the general formula (114), R41 to R46 each independently represent a hydrogen atom or a substituent,
wherein in the general formula (115), R71 to R80 each independently represent a hydrogen atom or a substituent.
Specific examples of the compounds include the compounds shown in the following tables. In the case where two or more groups represented by any one of the general formulae (112) to (115) are present In the molecule of the following example compounds, all the groups have the same structure. The formulae (121) to (124) in the tables represent the following formulae, respectively, and n represents the number of the repeating units.
500-1
500-2
500-3
500-4
500-5
500-6
500-7
500-8
500-9
Examples of the preferred light emitting material capable of emitting delayed fluorescent light include the following compounds.
wherein in the general formula (131), from 0 to 1 of R1 to R5 represents a cyano group, from 1 to 5 of R1 to R5 each represent a group represented by the following general formula (132), and the balance of R1 to R5 each represent a hydrogen atom or a substituent other than the above,
wherein in the general formula (132), R11 to R20 each independently represent a hydrogen atom or a substituent, in which R11 and R12, R12 and R13, R13 and R14, R14 end R15, R15 and R16, R16 and R17, R17 and R18, R18 and R19, and R19 and R20 each may be bonded to each other to forma ring structure; and L12 represents a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group.
wherein in the general formulae (133) to (138), R21 to R24, R27 to R38, R41 to R48, R51 to R58, R61 to R65, R71 to R79, R81 to R90 each independently represent a hydrogen atom or a substituent, in which R21 and R22, R22 and R23, R23 and R24, R27 and R28, R28 and R29, R29 and R30, R31 and R32, R32 and R33, R33 and R34, R35 and R36, R36 and R37, R37 and R38, R41 and R42, R42 and R43, R43 and R44, R45 and R46, R46 and R47, R47 and R48, R51 and R52, R52 and R53, R53 and R54, R55 and R56, R56 and R57, R57 and R58, R61 and R62, R62 and R63, R63 and R64, R64 and R65, R54 and R61, R55 and R65, R71 and R72, R72 and R73, R73 and R74, R74 and R75, R76 and R77, R77 and R78, R78 and R79, R81 and R82, R82 and R83, R83 and R84, R85 and R84, R86 and R87, R87 and R88, and R89 and R90 each may be bonded to each other to form a ring structure; and L13 to L18 each independently represent a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group.
Examples of the compound include the following compounds.
Examples of the preferred light emitting material include compounds represented by the following general formula (141). The entire description of WO 2013/011954 including the paragraphs 0007 to 0047 and 0073 to 0085 is incorporated herein by reference.
wherein in the general formula (141), R1, R2, R3, R4, R5, R6, R7, R8 and R17 each independently represent a hydrogen atom or an electron donating group, provided that at least one thereof represents an electron donating group; R9, R10, R11, R12, R13, R14, R15 and R16 each independently represent a hydrogen atom or an electron withdrawing group having no unshared electron pair at the α-position; and Z represents a single bond or >C═Y, wherein Y represents O, S, C(CN)2 or C(COOH)2, provided that when Z represents a single bond, at least one of R9, R10, R11, R12, R13, R14, R15 and R16 represents an electron withdrawing group having no unshared electron pair at the α-position.
Specific examples of the compounds include the compounds shown in the following tables. In the tables, D1 to D3 represent the following aryl groups substituted toy an electron donating group, respectively; A1 to A5 represent the following electron withdrawing groups, respectively; H represents a hydrogen atom; and Ph represents a phenyl group.
Examples of the preferred light emitting material include compounds represented by the following general formula (151). The entire description of WO 2013/011955 including the paragraphs 0007 to 0033 and 0059 to 0066 is incorporated herein by reference.
wherein in the general formula (151), R1, R2, R3, R4, R5, R6, R7, and R8 each independently represent a hydrogen atom or an electron donating group, provided that at least one thereof represents an electron donating group; R9, R10, R11, R12, R13, R14, R15 and R16 each independently represent a hydrogen atom or an electron withdrawing group, provided that at least one thereof represents an electron withdrawing group.
Specific examples of the compounds include the compounds shown in the following tables. In the tables, D1 to D10 represent the unsubstituted electron donating groups having the following structures, respectively.
Examples of the preferred light emitting material include compounds represented by the following general formula (161). The entire description of WO 2013/081088 including the paragraphs 0008 to 0071 and 0118 to 0133 is incorporated herein by reference.
wherein in the general formula (161), any two or Y1, Y2 and Y3 each represent a nitrogen atom, and the balance thereof represents a methine group, of all Y1, Y2, and Y3 each represent a nitrogen atom; Z1 and Z2 each independently represent a hydrogen atom or a substituent; and R1 to R8 each independently represent a hydrogen atom or a substituent, provided that at least one of R1 to R8 represents a substituted or unsubstituted diarylamino group or a substituted or unsubstituted carbazolyl group. The compound represented by the general formula (161) has at least two carbazole structures in the molecule thereof.
Examples of the compound include the following compounds.
Examples of the preferred light emitting material include compounds represented by the following general formula (181). The entire description of JP-A-2013-116975 including the paragraphs 0008 to 0020 and 0038 to 0040 is incorporated herein by reference.
wherein in the general formula (181), R1, R2, R4 to R8, R11, R12 and R14 to R18 each independently represent a hydrogen atom or a substituent.
Examples of the compound include the following compound.
Examples of the preferred light emitting material include the following compounds.
wherein in the general formula (191), Ar1 represents a substituted or unsubstituted arylene group; Ar2 and Ar3 each independently represent a substituted or unsubstituted aryl group; and R1 to R8 each independently represent a hydrogen atom or a substituent, provided that at least one of R1 to R8 represents a substituted or unsubstituted diarylamino group, and R1 and R8, R2 and R3, R3 and R4, R5 and R6, R6 and R7, and R7 and R8 each may be bonded to each other to form a cyclic structure.
wherein in the general formula (192), R1 to R8 and R11 to R24 each independently represent a hydrogen atom or a substituent, provided that at least one of R1 to R8 represents a substituted or unsubstituted diarylamino group, and R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, R7 and R8, R11 and R12, R12 and R13, R13 and R14, R14 and R15, R16 and R17, R17 and R18, R18 and R19, R19 and R20, R21 and R22, and R23 and R24 each may be bonded to each other to form a ring structure.
Specific examples of the compound include the following compounds. Ph represents a phenyl group.
Examples of the preferred light emit ting material include the following compounds.
wherein in the general formula (201), R1 to R8 each independently represent a hydrogen atom or a substituent, provided that at least one of R1 to R8 represents a substituted or unsubstituted carbazolyl group; and Ar1 to Ar3 each independently represent a substituted or unsubstituted aromatic ring or a heteroaromatic ring.
Specific examples of the compound include the following compounds.
Examples of the preferred light emitting material include compounds represented by the following general formulae (211) and (212). The entire description of WO 2013/133359 including the paragraphs 0007 to 0032 and 0079 to 0084 is incorporated herein by reference.
wherein in the general formula (211), Z1, Z2 and Z3 each independently represent a substituent.
wherein in the general formula (212), Ar1, Ar2, Ar3, Ar4, Ar5 and Ar6 each independently represent a substituted or unsubstituted aryl group.
Specific examples of the compound represented by the general formula (212) Include the compound represented by the following structural formula.
Specific examples of the compound represented by the general formula (212) include the compounds shown in the following table. In the compounds shown in the table, Ar1, Ar2, Ar3, Ar4, Ar5 and Ar6 are the same as each other, and are expressed by Ar.
Examples of the preferred light emitting material include compounds represented by the following general formula (221). The entire description of WO 2013/161437 including the paragraphs 0008 to 0054 and 0101 to 0121 is incorporated herein by reference.
wherein in the general formula (221), R1 to R10 each independently represent a hydrogen atom or a substituent, provided that at least one of R1 to R10 represents a substituted or unsubstituted aryl group, a substituted or unsubstituted diarylamino group or a substituted or unsubstituted 9-carbasolyl group, and R1 and R2, R2 and R3, R3 and R4, R4 and R5, R5 and R6, R6 and R7, R7 and R8, R8 and R9, and R9 and R10 each may be bonded to each other to form a ring structure.
Specific examples of the compound include the following compounds.
Examples of the preferred light emitting material include compounds represented by the following general formula (231). The entire description of JP-A-2014-9352 including the paragraphs 0007 to 0041 and 0060 to 0069 is incorporated herein by reference.
wherein in the general formula (231), R1 to R4 each independently represent a hydrogen atom or a substituted or unsubstituted (N,N-diarylamino)aryl group, provided that at least one of R1 to R4 represents a substituted or unsubstituted (N,N-diarylamino)aryl group, and two aryl groups constituting the diarylamino moiety of the (N,N-diarylamino)aryl group may be bonded to each other; W1, W2, X1, X2, Y1, Y2, Z1 and Z2 each independently represent a carbon atom or a nitrogen atom; and m1 to m4 each independently represent 0, 1 or 2.
Specific examples of the compound include the following compounds.
Examples of the preferred light emitting material include compounds represented by the following general formula (241). The entire description of JP-A-2014-9224 including the paragraphs 0008 to 0048 and 0067 to 0076 is incorporated herein by reference.
wherein in the general, formula (241), R1 to R6 each independently represent a hydrogen atom or a substituent, provided that at least one of R1 to R6 represents a substituted or unsubstituted (N,N-diarylamino)aryl group, and two aryl groups constituting the diarylamino moiety of the (N,N-diarylamino)aryl group may be bonded to each other; X1 to X6 and Y1 to Y6 each independently represent a carbon, atom or a nitrogen atom; and n1, n2, p1, p2, q1 and q2 each independently represent 0, 1 or 2.
Specific examples of the compound include the following compounds.
Examples of the preferred light emitting material include the following compounds.
wherein in the general formula (251), one of A1 to A7 represents N, and the balance each independently represent C—R; R represents a non-aromatic group; Ar1 to Ar3 each independently represent a substituted or unsubstituted arylene group; and Z represents a single bond or a linking group.
wherein in the general formula (252), 1 to 4 of A1 to A7 represents N, and the balance each independently represent C-R; R represents a non-aromatic group; Ar1 represents a substituted or unsubstituted arylene group; R11 to R14 and R17 to R20 each independently represent a hydrogen atom or a substituent, in which R11 and R12, R12 and R13, R13 and R14, R17 and R18, R18 and R19, and R19 and R20 each may be bonded to each other to form a cyclic structure; and Z1 represents a single bond or a linking group having 1 or 2 linking chain atoms.
wherein in the general, formula (253), from 2 to 4 of A1 to A7 represent N, and the balance represent C-R; R represents a non-aromatic group; Ar1 represents a substituted or unsubstituted arylene group; and Y represents a substituted or unsubstituted carbazol-9-yl group, a substituted or unsubstituted 10H-phenoxazin-10-yl group, a substituted or unsubstituted 10H-phenothiazin-10-yl group, or a substituted or unsubstituted 10H-phenazin-5-yI group.
wherein in the general formulae (254) to (257), R21 to R24, R27 to R38, R41 to R48, R51 to R58, and R61 to R65 each independently represent a hydrogen atom or a substituent, in which R21 and R22, R22 and R23, R23 and R24, R27 and R28, R28 and R29, R29 and R30, R31 and R32, R32 and R33, R33 and R34, R35 and R36, R36 and R37, R37 and R38, R41 and R42, R42 and R43, R43 and R44, R45 and R46, R46 and R47, R47 and R48, R51 and R52, R52 and R53, R53 and R54, R55 and R56, R56and R57, R57 and R58, R61 and R62, R62 and R63, R63 and R64, R64 and R65, R54 and R61, and R55 and R65 each may be bonded to each other to form a cyclic structure.
wherein in the general formula (258), R21′ to R24′ and R27′ to R30′ each independently represent a hydrogen atom or a substituent, provided that at least one of R23′ and R28′ represents a substituent, and R21′ and R22′, R22′ and R23′, R23′ and R24′, R27′ and R28′, R28′ and R29′, and R29′ and R30′ each may be bonded to each other to form a cyclic structure.
Examples of the compound include the following compounds.
Examples of the preferred light emitting material include the following compounds.
wherein in the general formula (271), R1 to R10 each independently represent a hydrogen atom or a substituent, provided that at least one of R1 to R10 each independently represent a group represented by the following general formula (272), and R1 and R2, R2 and R3, R3 and R4, R4 and R5, R6 and R7, R7 and R8, R8 and R9, and R9 and R10 each may be bonded to each other to form a cyclic structure:
wherein in the general formula (272), R11 to R20 each independently represent a hydrogen atom or a substituent, in which R11 and R12, R12 and R13, R13 and R14, R14 and R15, R15 and R16, R16 and R17, R17 and R18, R18 and R19, and R19 and R20 each may be bonded to each other to form a cyclic structure; Ph represents a substituted or unsubstituted phenylene group; and n1 represents 0 or 1.
wherein in the general formulae (273) to (278), R21 to R24, R27 to R28, R41 to R48, R51 to R58, R61 to R65, R71 to R79, and R81 to R90 each independently represent a hydrogen atom or a substituent, in which R21 and R22, R22 and R23, R23 and R24, R27 and R28, R28 and R29, R29 and R30, R31 and R32, R32 and R33, R33 and R34, R35 and R36, R36 and R37, R37 and R38, R41 and R42, R42 and R43, R43 and R44, R45 and R46, R46 and R47, R47 and R48, R51 and R52, R52 and R53, R53 and R54, R55 and R56, R56and R57, R57 and R58, R61 and R62, R62 and R63, R63 and R64, R64 and R65, R54 and R61, R55 and R65, R71 and R72, R72and R73, R73 and R74, R74 and R75, R76 and R77, R77 and R78, R78 and R79, R81 and R82, R82 and R83, R83 and R84, R85 and R86, R86 and R87, R87 and R88, and R89 and R90 each may be bonded to each other to form a cyclic structure; Ph represents a substituted or unsubstituted phenylene group; and n1 represents 0 or 1.
Examples of the compound include the following compounds.
Examples of the preferred light emitting material include the following compounds.
wherein in the general formula (281), X represents an oxygen atom or a sulfur atom; R1 to R8 each independently represent a hydrogen atom or a substituent, provided that at least one of R1 to R8 represents a group represented by any one of the following general formulae (282) to (287), and R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, R7 and R8, R8 and R9, and R9 and R1 may be bonded to each other to farm a cyclic structure; and R9 represents a substituent, provided that when R9 contains an atom that contains a lone electron pair without forming a single bond to the boron atom, the atom may form a cyclic structure through a coordination bond with the boron atom:
wherein in the general formulae (282) to (287), L12 to L17 each independently represent a single bond or a divalent linking group; * represent the position bonded to the benzene ring in the general formula (281); and R11 to R20, R21 to R28, R31 to R38, R3a, R3b, R41 to R48, R4a, R51 to R58, R61 to R68 each independently represent a hydrogen atom or a substituent, in which R11 and R12, R12 and R13, R13 and R14, R14 and R15, R16 and R17, R17 and R18, R18 and R19, R19 and R20, R21 and R22, R22 and R23, R23 and R24, R24 and R25, R25 and R26, R26 and R27, R27 and R28, R31 and R32, R32 and R33, R33 and R34, R35 and R36, R36 and R37, R37 and R38, R3a and R3b, R41 and R42, R42 and R43, R43 and R44, R45 and R46, R46 and R47, R47 and R48, R51 and R52, R52 and R53, R53 and R54, R55 and R56, R56 and R57, R57 and R58, R61 and R62, R62 and R63, R63 and R64, R65 and R66, R66 and R67, and R67 and R68 each may be bonded to each other to form a cyclic structure.
wherein in the general formula (a), * represents the position bonded to the boron atom in the general formula (281); and R9a, R9b, R9c, R9d, and R9e each independently represent a hydrogen atom or a substituent, in which R9a and R9b, R9b and R9c, R9c and R9d, and R9d and R9e may be bonded to each other to form a cyclic structure.
Examples of the compound include the following compounds.
Examples of the preferred light emitting material include the following compounds.
wherein in the general formula (291), X represents O, S, N—R11, C═O, C(R12)(R13), or Si(R14)(R15); Y represents O, S, or N—R16; Ar1 represents a substituted or unsubstituted arylene group; Ar2 represents an aromatic ring or a heteroaromatic ring; and R1 to R8 and R11 to R16 each independently represent a hydrogen atom or a substituent, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, and R7 and R8 each may be bonded to each other to form a cyclic structure.
wherein in the general formula (292), X represents O, S, N—R11, C═O, C(R12)(R13), or Si(R14)(R15); Y represents O, S, or N—R16; Ar2 represents an aromatic ring or a heteroaromatic ring; and R1 to R8, R11 to R18, and R21 to R24 each independently represent a hydrogen atom or a substituent, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, R7 and R8, R21 and R22, and R23 and R24 each may be bonded to each other to form a cyclic structure.
wherein in the general formula (293), X represents O, S, N—R11, C═O, C(R12)(R13), or Si(R14)(R15); Y represents O, S, or N—R16; and R1 to R8, R11 to R16, R21 to R24, and R31 to R34 each independently represent a hydrogen atom or a substituent, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, R7 and R8, R21 and R22, R23 and R24, R31 and R32, R32 and R33, and R33 and R34 each my be bonded to each other to form a cyclic structure.
Examples of the compound include the following compounds.
Examples of the preferred light emitting material include the following compounds.
(Dn)-A General Formula (301)
wherein in the general formula (301), D represents a group represented toy the following general formula (302); A represents an n-valent group containing a structure represented toy the following general formula (303); and n represents an integer of from 1 to 8:
wherein in the general formula (302), Z1 represents O, S, C═O, C(R21)(R22), Si(R23)(R24), N-Ar3, or a single bond; R21 to R24 each independently represent an alkyl group having from 1 to 8 carbon atoms; Ar3 represents a substituted or unsubstituted aryl group; and R1 to R8 each independently represent a hydrogen atom or a substituent, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, and R7 and R8 may be bonded to each other to form a cyclic structure, and when Z1 represents a single bond, at least one of R1 to R8 represents a substituted or unsubstituted diarylamino group:
wherein in the general formula (303), Y represents O, S, or N-Ar4; and Ar4 represents a substituted or unsubstituted aryl group.
wherein in the general, formula (304), Y represents O, S, or N-Ar4; and Ar1 and Ar2 each independently represent a substituted or unsubstituted aromatic group.
wherein in the general formula (305), Z1 and Z2 each independently represent O, S, C═O, C(R21)(R24), Si(R23)(R24), N-Ar3, or a single bond; R21 to R24 each independently represent an alkyl group having from 1 to 8 carbon atoms; Ar3 represents a substituted or unsubstituted aryl group; Ar1 and Ar2 each independently represent a substituted or unsubstituted aromatic group; Y represents O, S, or N-Ar4; Ar4 represents a substituted or unsubstituted aryl group; R1 to R8 and R11 to R18each independently represent a hydrogen atom or a substituent, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, R7 and R8, R11 and R12, R12 and R13, R13 and R14, R15 and R16, R16 and R17, and R17 and R18 each may be bonded to each other to form a cyclic structure, provided that when Z1 represents a single bond, at least one of R1 to R8 represents a substituted or unsubstituted diarylamino group, and when Z2 represents a single bond, at least one of R11 to R18 represents a substituted or unsubstituted diarylamino group; and n1 and n2 each independently represent an integer of from 0 to 8, provided that the sum of n1 and n2 is from 1 to 8.
wherein in the general formula (306), Z1 represents O, S, C═O, C(R21)(R24), Si(R23)(R24), N-Ar3, or a single bond; R21 to R24 each independently represent an alkyl group having from 1 to 8 carbon atoms; Ar3 represents a substituted or unsubstituted aryl group; Ar1′ represents a substituted or unsubstituted arylene group; Ar2′ represents a substituted or unsubstituted aryl group; Y represents O, S, or N-Ar4; Ar4 represents a substituted or unsubstituted aryl group; and R1 to R8 each independently represent a hydrogen atom or a substituent, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, and R7 and R8 each may be bonded to each other to form a cyclic structure, provided that when Z1 represents a single bond, at least one of R1 to R8 represents a substituted or unsubstituted diarylamino group.
wherein in the general formula (307), Z1 and Z2 each independently represent O, S, C═O, C(R21)(R24), Si(R23)(R24), N-Ar3, or a single bond; R21 to R24 each independently represent an alkyl group having from 1 to 8 carbon atoms; Ar3 represents a substituted or unsubstituted aryl group; Ar1″ and Ar2″ each independently represent a substituted or unsubstituted arylene group; Y represents O, S, or N-Ar4; Ar4 represents a substituted or unsubstituted aryl group; and R1 to R8 and R11 to R18 each independently represent a hydrogen atom or a substituent, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, R7 and R8, R11 and R12, R12 and R13, R13 and R14, R15 and R16, R16 and R17, and R17 and R18 each may be bonded to each other to form a cyclic structure, provided that when Z1 represents a single bond, at least one of R1 to R8 represents a substituted or unsubstituted diarylamino group, and when Z2 represents a single bond, at least, one of R11 to R18 represents a substituted or unsubstituted diarylamino group.
Examples of the compound include the following compounds.
Examples of the preferred light emitting material include the following compounds.
A-D-A General Formula (311)
wherein in the general formula (311), D represents a divalent, group containing a structure represented by the following formula (in which hydrogen atoms in the structure each may be substituted by a substituent):
and two groups represented by A each independently are a group having a structure selected from the following group (in which hydrogen atoms in the structure each may be substituted by a substituent):
wherein in the general formula (312), R1 to R8 each independently represent a hydrogen atom or a substituent, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, and R7 and R8 each may be bonded to each other to form a cyclic structure.
wherein in the general formula (313), R1 to R8 and R11 to R20 each independently represent a hydrogen atom or a substituent, in which R1 and R2, R2 and R3, R3 and R4, R5 and R6, R6 and R7, R7 and R8, R11 and R12, R12 and R13, R13 and R14, R14 and R15, R16 and R17, R17 and R18, R18 and R19, and R19 and R20 each may be bonded to each other to form a cyclic structure, provided that the general formula (313) satisfies the following conditions <1> and <2>:
or
or
and
or
or
Examples of the compound include the following compounds.
The molecular weight of the second organic compound is preferably 1,500 or less, more preferably 1,200 or less, further preferably 1,000 or less, and still further preferably 800 or less, for example, in the case where a light emitting layer containing the second organic compound is intended to be formed as a film by a vapor deposition method. The lower limit of the molecular weight, for example, of the compound represented by the general formula (1) or (9) is the molecular weight of the smallest compound represented by the general formula.
In the case where the light emitting layer is formed by a coating method, the compound that has a relatively large molecular weight may also be preferably used irrespective of the molecular weight thereof.
In the present invention, the delayed fluorescent material that is capable of being used as the second organic compound is not limited to the compound represented by the general formula (1), and any delayed fluorescent material that satisfies the expression (A) other than the compounds represented by the general formula (1) may be used. Examples of the delayed fluorescent material include compounds having a structure obtained by replacing the triazine skeleton of the general formula (1) by a pyridine skeleton, and compounds having a benzophenone skeleton or a xanthone skeleton having various heterocyclic structures substituted thereon.
The first organic compound is an organic compound having the lowest singlet excitation energy that is larger than those of the second organic compound and the third organic compound, and has a function as a host material assuming the transfer of the carrier and a function of confining the energy of the third organic compound within the compound. Due to the use of the first organic compound, the third organic compound can efficiently convert the energy formed through recombination of holes and electrons in the compound and the energy received from the first organic compound and the second organic compound to the light emission, and thus an organic electroluminescent device having a high light emission efficiency can be achieved.
The first organic compound is preferably such an organic compound that has a bole transporting function and an electron transporting function, prevents the light emission from having a longer wavelength, and has a high glass transition temperature. Examples of the preferred compound capable of being used as the first organic compound are shown below. In the structural formulae of the example compounds, R and R1 to R10 each independently represent a hydrogen atom or a substituent, and n represents an integer of from 3 to 5.
The third organic compound is a light emitting material having the lowest singlet excitation energy that is smaller than those of the first organic compound and the second organic compound. The third organic compound is transferred to the singlet excited state through reception of energy from the first organic compound and the second organic compound that are in the singlet excited state and the second organic compound that is in the singlet excited state that is achieved through the inverse intersystem crossing from the triplet excited state, and emits fluorescent light on returning to the ground state. The light emitting material used as the third organic compound is not particularly limited, as far as the compound is capable of emitting light through reception of energy from the first organic compound and the second organic compound, and the light emission thereof may be fluorescence, delayed fluorescence, or phosphorescence. Among the compounds, the light emitting material used as the third organic compound is preferably a compound that emits fluorescent light on returning from the lowest singlet excitation energy level to the ground energy level. The third organic compound used may be two or more kinds of compounds, as far as the compounds satisfy the relationship of the expression (A). For example, the use of two or more kinds of the third organic compounds having different light emission colors may enable light emission with a desired color.
Examples of the preferred compounds capable of being used as the third organic compound are shown below for the light emission colors. In the structural formulae of the example compounds, Et represents an ethyl group, and i-Pr represents an isopropyl group.
In addition to the aforementioned compounds for light emission colors, the following compounds may also be used as the third organic compound.
The contents of the organic compounds contained in the light emitting layer are not particularly limited, and the content of the second organic compound is preferably smaller than the content of the first organic compound, by which a higher light emission efficiency may be obtained. Specifically, assuming that the total weight of the content W1 of the first organic compound, the content W2 of the second organic compound, and the content W3 of the third organic compound is 100% by weight, the content W1 of the first organic compound is preferably 15% by weight or more and 99.9% by weight or less, the content W2 of the second organic compound is preferably 5.0% by weight or more and 50% by weight or less, and the content W3 of the third organic compound is preferably 0.5% by weight or more and 5.0% by weight or less.
The light emitting layer may be constituted only by the first to third organic compounds, and may contain an additional organic compound other than the first to third organic compounds. Examples of the additional organic compound other than the first to third organic compounds include an organic compound having a hole transporting function and an organic compound having an electron transporting function. For examples of the organic compound having a hole transporting function and the organic compound having an electron transporting function, reference may be made to the hole transporting materials and the electron transporting materials described later.
The organic electroluminescent device of the invention is preferably supported by a substrate. The substrate is not particularly limited and may be those that have been commonly used in an organic electroluminescent device, and examples thereof used include those formed of glass, transparent, plastics, quartz and silicon.
The anode of the organic electroluminescent device used is preferably formed of as an electrode material a metal, an alloy or an electroconductive compound each having a large work function (4 eV or more), or a mixture thereof. Specific examples of the electrode material include a metal, such as Au, and an electroconductive transparent material, such as CuI, indium tin oxide (ITO), SnO2 and ZnO. A material that is amorphous and is capable of forming a transparent electroconductive film, such as IDIXO (In2O3—ZnO), may also be used. The anode may be formed in such a manner that the electrode material is formed into a thin film by such a method as vapor deposition or sputtering, and the film is patterned into a desired pattern by a photolithography method, or in the case where the pattern may not require high accuracy (for example, approximately 100 μm or more), the pattern may be formed with a mask having n desired shape on vapor deposition or sputtering of the electrode material. In alternative, in the case where a material capable of being applied as a coating, such as an organic electroconductive compound, is used, a wet film forming method, such as a printing method and a coating method, may be used. In the case where emitted light is to be taken out through the anode, the anode preferably has a transmittance of more than 10%, and the anode preferably has a sheet resistance of several hundred ohm per square or less. The thickness thereof may be generally selected from a range of from 10 to 1,000 nm, and preferably from 10 to 200 nm, while depending on the material used.
The cathode is preferably formed of as an electrode material a metal having a small work function (4 eV or less) (referred to as an electron injection metal), an alloy or an electroconductive compound each having a small work function (4 eV or less), or a mixture thereof. Specific examples of the electrode material include sodium, a sodium-potassium alloy, magnesium, lithium, a magnesium-cupper mixture, a magnesium-silver mixture, a magnesium-aluminum mixture, a magnesium-indium mixture, an aluminum-aluminum oxide (Al2O3) mixture, indium, a lithium-aluminum mixture, and a rare earth metal. Among these, a mixture of an electron injection metal and a second metal that is a stable metal having a larger work function than the electron injection metal, for example, a magnesium-silver mixture, a magnesium-aluminum mixture, a magnesium-indium mixture, an aluminum-aluminum oxide (Al2O3) mixture, a lithium-aluminum mixture, and aluminum, are preferred from the standpoint of the electron injection property and the durability against oxidation and the like. The cathode may be produced by forming the electrode material into a thin film by such a method as vapor deposition or sputtering. The cathode preferably has a sheet resistance of several hundred ohm per square or less, and the thickness thereof may be generally selected from a range of from 10 nm to 5 μm, and preferably from 50 to 200 nm. For transmitting the emitted light, any one of the anode and the cathode of the organic electroluminescent device is preferably transparent, or translucent, thereby enhancing the light, emission luminance.
The cathode may be formed with the electroconductive transparent materials described for the anode, thereby forming a transparent or translucent cathode, and by applying the cathode, a device having an anode and a cathode, both of which have transmittance, may be produced.
The injection layer is a layer that is provided between the electrode and the organic layer, for decreasing the driving voltage and enhancing the light emission luminance, and includes a hole injection layer and an electron injection layer, which may be provided between the anode and the light emitting layer or the hole transporting layer and between the cathode and the light emitting layer or the electron transporting layer. The injection layer may be provided depending on necessity.
The barrier layer is a layer that is capable of inhibiting charges (electrons or holes) and/or excitons present in the light emitting layer from being diffused outside the light emitting layer. The electron barrier layer may be disposed between the light emitting layer and the hole transporting layer, and inhibits electrons from passing through the light emitting layer toward the hole transporting layer. Similarly, the hole barrier layer may be disposed between the light emitting layer and the electron transporting layer, and inhibits holes from passing through the light emitting layer toward the electron transporting layer. The barrier layer may also be used for inhibiting excitons from being diffused outside the light emitting layer. Thus, the electron barrier layer and the hole barrier layer each may also have a function as an exciton barrier layer. The term “the electron barrier layer” or “the exciton barrier layer” referred herein is intended to include a layer that has both the functions of an electron barrier layer and an exciton barrier layer by one layer.
The hole barrier layer has the function of an electron transporting layer in a broad sense. The hole barrier layer has a function of inhibiting holes from reaching the electron transporting layer while transporting electrons, and thereby enhances the recombination, probability of electrons and holes in the light emitting layer. As the material for the hole barrier layer, the materials for the electron transporting layer described later may be used depending on necessity.
The electron barrier layer has the function of transporting holes in a broad sense. The electron barrier layer has a function of inhibiting electrons from reaching the hole transporting layer while transporting holes, and thereby enhances the recombination probability of electrons and holes in the light emitting layer.
The exciton barrier layer is a layer for inhibiting excitons generated through recombination of holes and electrons in the light emitting layer from being diffused to the charge transporting layer, and the use of the layer inserted enables effective confinement of excitons in the light emitting layer, and thereby enhances the light emission efficiency of the device. The exciton barrier layer may be Inserted adjacent to the light emitting layer on any of the side of the anode and the side of the cathode, and on both the sides. Specifically, in the case where the exciton barrier layer is present on the side of the anode, the layer may be inserted between the hole transporting layer and the light emitting layer and adjacent to the light emitting layer, and in the case where the layer is inserted on the side of the cathode, the layer may be inserted between the light emitting layer and the cathode and adjacent to the light emitting layer. Between the anode and the exciton barrier layer that is adjacent to the light emitting layer on the side of the anode, a hole injection layer, an electron barrier layer and the like may be provided, and between the cathode and the exciton barrier layer that is adjacent to the light emitting layer on the side of the cathode, an electron injection layer, an electron transporting layer, a hole barrier layer and the like may be provided. In the case where the barrier layer is provided, the material used for the barrier layer preferably has excited singlet energy and excited triplet energy, at least one of which is higher than the excited singlet energy and the excited triplet energy of the light, emitting material, respectively.
The hole transporting layer is formed of a hole transporting material having a function of transporting holes, and the hole transporting layer may be provided as a single layer or plural layers.
The hole transporting material has one of injection or transporting property of holes and barrier property of electrons, and may be any of an organic material and an inorganic material. Examples of known hole transporting materials that may be used herein include a triazole derivative, an oxadiazole derivative, an imidazole derivative, a carbazole derivative, an indolocarbazole derivative, a polyarylalkane derivative, a pyrazoline derivative, a pyrazolone derivative, a phenylenediamine derivative, an arylamine derivative, an amino-substituted chalcone derivative, an oxazole derivative, a styrylanthracene derivative, a fluorenone derivative, a hydrazone derivative, a stilbene derivative, a silazane derivative, an aniline copolymer and an electroconductive polymer oligomer, particularly a thiophene oligomer. Among these, a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound are preferably used, and an aromatic tertiary amine compound is more preferably used.
The electron transporting layer is formed of a material having a function of transporting electrons, and the electron transporting layer may be provided as a single layer or plural layers.
The electron transporting material (which may also function as a hole barrier material in some cases) needs only to have a function of transporting electrons, which are injected from the cathode, to the light emitting layer. Examples of the electron transporting layer that may be used herein include a nitro-substituted fluorene derivative, a diphenylquinone derivative, a thiopyran dioxide derivative, carbodiimide, a fluorenylidane methane derivative, anthraquinodimethane and anthrone derivatives, and an oxadiazole derivative. The electron transporting material used may be a thiadiazole derivative obtained by replacing the oxygen atom of the oxadiazole ring of the oxadiazole derivative by a sulfur atom, or a quinoxaline derivative having a quinoxaline ring, which is known as an electron attracting group. Furthermore, polymer materials having these materials introduced to the polymer chain or having these materials used as the main chain of the polymer may also be used.
In the production of the organic electroluminescent device, the compound represented by the general formula (1) not only may be used in the light emitting layer, but also may be used in the other layers than the light emitting layer. In this case, the compound represented by the general formula (1) used in the light emitting layer and the compound represented by the general formula (1) used in the other layers than the light emitting layer may be the same as or different from each other. For example, the compound represented by the general formula (1) may be used in the injection layer, the barrier layer, the hole barrier layer, the electron barrier layer, the exciton barrier layer, the hole transporting layer, the electron transporting layer and the like described above. The film forming method of the layers are not particularly limited, and the layers may be produced by any of a dry process and a wet process.
Specific examples of preferred materials that may be used in the organic electroluminescent device are shown below, but the materials that may be used in the invention are not construed as being limited to the example compounds. The compound that is shown as a material having a particular function may also be used as a material having another function. In the structural formulae of the example compounds, R and R2 to R7 each independently represent a hydrogen atom or a substituent, and n represents an integer of from 3 to 5.
Preferred examples of a compound that, may be used as the hole injection material are shown below.
Preferred examples of a compound that way be used as the hole transporting material are shown below.
Preferred examples of a compound that may be used as the electron barrier material are shown below.
Preferred examples of a compound that may be used as the hole barrier material are shown below.
Preferred examples of a compound that may be used as the electron transporting material are shown below.
Preferred examples of a compound that may be used as the electron injection material are shown below.
Preferred examples of a compound as a material that may be added are shown below. For example, the compound may be added as a stabilizing material.
The organic electroluminescent device thus produced by the aforementioned method emits light on application of an electric field between the anode and the cathode of the device. In this case, when the light emission is caused by the singlet, excitation energy, light having a wavelength that corresponds to the energy level thereof may be confirmed as fluorescent light and delayed fluorescent light. When the light emission is caused by the triplet excitation energy, light having a wavelength that corresponds to the energy level thereof may be confirmed as phosphorescent light. The normal fluorescent light has a shorter light emission lifetime than the delayed fluorescent light, and thus the light emission lifetime may be distinguished between the fluorescent light and the delayed fluorescent light.
On the other hand, phosphorescent light is substantially not observed at room temperature since in an ordinary organic compound, such as the compound of the invention, the triplet excitation energy is converted to heat or the like due to the instability thereof, and thus is immediately deactivated with a short lifetime. The triplet excitation energy of the ordinary organic compound may be measured only by observing light emission under an extremely low temperature condition.
The organic electroluminescent device of the invention may be applied to any of a single device, a structure with plural devices disposed in an array, and a structure having anodes and cathodes disposed in an X-Y matrix. According to the invention, an organic light emitting device that is largely improved in light emission efficiency may be obtained by adding the compound represented by the general formula (1) in the light emitting layer. The organic light emitting device, such as the organic electroluminescent device, of the invention may be applied to a further wide range of purposes. For example, an organic electroluminescent display apparatus may be produced with the organic electroluminescent device of the invention, and for the details thereof, reference may be made to S. Tokito, C. Adachi and H. Murata, “Yuki EL Display” (Organic EL Display) (Ohmsha, Ltd.). In particular, the organic electroluminescent device of the invention may be applied to organic electroluminescent illumination and backlight which are highly demanded.
The features of the invention will be described more specifically with reference to examples below. The materials, processes, procedures and the like shown below may be appropriately modified unless they deviate from the substance of the invention. Accordingly, the scope of the invention is not construed as being limited to the specific examples shown below. The light emission characteristics were evaluated by using High-performance UV/Vis/NIR Spectrophotometer (Lambda 950, produced by PerkinElmer, Co., Ltd.), Fluorescence Spectrophotometer (FluoroMax-4, produced by Horiba, Ltd.), Absolute PL Quantum Yield Measurement System (C11347, produced by Hamamatsu Photonics K.K.), Source Meter (2400 Series, produced by Keithley Instruments Inc.), Semiconductor Parameter Analyzer (E5273A, produced by Agilent Technologies, Inc.), Optical Power Meter (1930C, produced by Newport Corporation), Fiber Optic Spectrometer (USB2000, produced by Ocean Optics, Inc.), Spectroradiometer (SR-3, produced by Topcon Corporation), and Streak Camera (Modal C4334, produced by Hamamatsu Photonics K.K.).
The lowest singlet excitation energy level ES1 and the lowest triplet excitation energy level ET1 of the compounds used in Examples and Comparative Examples were measured in the following procedures. The energy difference ΔEst between the lowest singlet excited state and the lowest triplet excited state at 77 K was obtained by measuring the difference between ES1 and ET1.
The compound to be measured was vapor-deposited on a Si substrate to produce a specimen, and the specimen was measured for a fluorescent spectrum at ordinary temperature (300 K). In the fluorescent spectrum, the ordinate Is the light emission, and the abscissa is the wavelength. A tangent line was drawn for the downfalling part of the light emission spectrum on the short wavelength side, and the wavelength λedge (nm) of the intersection point of the tangent line and the abscissa was obtained. The wavelength value was converted to an energy value according to the following conversion expression to provide the singlet energy ES1.
ES1(eV)═1239.85/λedge Conversion Expression
The light emission spectrum was measured with a nitrogen laser (MNL200, produced by Lasertechnik Berlin GmbH) as an excitation light source and Streak Camera (C4334, produced by Hamamatsu Photonics K.K.) as a detector.
The same specimen as used for the singlet energy ES1 was cooled to 77 K, the specimen for measuring phosphorescent light was irradiated with excitation light (337 nm), and the phosphorescence intensity was measured with a streak camera. A tangent line was drawn for the upstanding part of the phosphorescent spectrum on the short wavelength side, and the wavelength λedqe (nm) of the intersection point of the tangent line and the abscissa was obtained. The wavelength value was converted to an energy value according to the following conversion expression to provide the singlet energy ET1.
ET1(eV)═1239.85/λedge Conversion Expression
The tangent line for the upstanding part of the phosphorescent spectrum on the short wavelength side was drawn in the following manner. Over the range in the phosphorescent spectrum curve of from the short wavelength end to the maximum peak value closest to the short wavelength end among the maximum peak values of the spectrum, a tangent line was assumed while moving within the range toward the long wavelength side. The gradient of the tangent line was increased while the curve was standing up (i.e., the value of the ordinate was increased). The tangent line that was drawn at the point where the gradient thereof became maximum was designated as the tangent line for the upstanding part of the phosphorescent spectrum on the short wavelength side.
A maximum peak having a peak intensity that was 10% or less of the maximum peak point intensity of the spectrum was not included in the maximum peak values and thus was not designated as the maximum peak value closest to the short wavelength end, and the tangent line that was drawn at the point where the gradient became maximum that was closest to the maximum peak value closest to the short wavelength end was designated as the tangent line for the upstanding part of the phosphorescent spectrum on the short wavelength side.
Production and Evaluation of Organic Electroluminescent Devices using mCBP (First Organic Compound), PXZ-TRZ (Second Organic Compound), and TBRb (Third Organic Compound)
The following organic compounds were prepared as materials of a light emitting layer.
mCBP has a lowest singlet excitation energy level ES1 of 2.7 eV and a lowest triplet excitation energy level ET1 of 2.90 eV, PXZ-TRZ has a lowest singlet excitation energy level ES1 of 2.3 eV and a lowest triplet excitation energy level ET1 of 2.23 eV, and TBRb has a lowest singlet excitation energy level ES1 of 2.18 eV.
An organic electroluminescent device was produced by using mCBP, PXZ-TRZ, and TBRb as materials of a light emitting layer.
Thin films ware laminated on a glass substrate having formed thereon an anode formed of indium tin oxide (ITO) having a thickness of 110 nm, by a vacuum vapor deposition method at a vacuum degree of 5.0×10−5 Pa or less. Firstly, HATCN was formed to a thickness of 10 nm on ITO, and thereon TrisPCz was formed to a thickness of 30 nm. mCBP, PXZ-TRZ, and TBRb were then vapor-co-deposited from separate vapor deposition sources to form a layer having a thickness of 15 nm, which was designated as a light emitting layer. At this time, the concentration of PXZ-TRZ was selected from a range of from 10 to 50% by weight, and the concentration of TBRb was 1% by weight. T2T was then formed to a thickness of 10 nm, and thereon BPyTP2 was formed to a thickness of 55 nm. Lithium fluoride (LiF) was then vacuum vapor-deposited to a thickness of 0.8 nm, and then aluminum (AL) was vapor-deposited to a thickness of 100 nm to form a cathode, thereby producing organic electroluminescent devices having various compositional ratios of the light emitting layer.
Production and Evaluation of Organic Electroluminescent Device using mCBP and TBRb
An organic electroluminescent device was produced in the same manner as in Example 1 except that in the production of the light emitting layer, the vapor deposition source for PXZ-TRZ was not used to forma vapor deposition film containing mCBP and 1% by weight of TBRb.
Production and Evaluation of Organic Electroluminescent Device Using PXZ-TRZ and TBRb
An organic electroluminescent device was produced in the same manner as in Example 1 except that in the production of the light emitting layer, the vapor deposition source for mCBP was not used to form a vapor deposition film containing only PXZ-TRZ and 1% by weight of TBRb.
Production and Evaluation of Organic Electroluminescent Device using mCBP and PXZ-TRZ
An organic electroluminescent device was produced in the same manner as in Example 1 except that in the production of the light emitting layer, the vapor deposition source for TBRb was not used to form a vapor deposition film containing mCBP and 25% by weight of PXZ-TRZ.
The characteristic values of the organic electroluminescent devices obtained from the characteristic graphs are shown in Table 22, and the initial luminances in the measurement of the transient decay curves shown in
As shown in Table 22, the organic electroluminescent device of Example 1 having a light emitting layer containing mCBP, PXZ-TRZ, and TBRb had a considerably high external quantum efficiency and a considerably high current efficiency and thus had excellent characteristics, as compared to the organic electroluminescent device of Comparative Example 1 using no PXZ-TRZ and the organic electroluminescent device of Comparative Example 2 using no mCBP.
As shown in Table 23, the organic electroluminescent device of Example 1 had a far longer luminance half-life period than the organic electroluminescent device of Comparative Example 1 using no PXZ-TRZ and the organic electroluminescent device of Comparative Example 3 using no TBRb.
It was found from
Production and Evaluation of Organic Electroluminescent Device using ADN (First Organic Compound), PXZ-TRZ (Second Organic Compound), and TBRb (Third Organic Compound)
An electroluminescent device was produced and evaluated in the same manner as in Example 1 except that ADN was used as the first organic compound instead of mCBP in Example 1. ADN has a lowest singlet excitation energy level ES1 of 2.83 eV and a lowest triplet excitation energy level ET1 of 1.69 eV. Light emission at a wavelength of approximately 560 nm was observed from the organic electroluminescent device of Example 2.
The organic electroluminescent device of Example 1 achieved an external quantum efficiency that was significantly higher than the organic electroluminescent device of Example 2, and thus was confirmed to have considerably excellent characteristics.
Production and Evaluation of 4-Element Organic Electroluminescent Device using mCBP (First Organic Compound), PXZ-TRZ (Second Organic Compound), TBRb (Third Organic Compound A), and DBP (Third Organic Compound B)
While, the organic electroluminescent device was produced by using only TBRb as the third organic compound in Example 1, an organic electroluminescent device was produced and evaluated by using further DBP shown below as the third organic compound in this example. DBP has a lowest singlet excitation energy level ES1 of 2.0 eV.
Thin films were laminated on a glass substrate having formed thereon an anode formed of indium tin oxide (ITO) having a thickness of 110 nm, by a vacuum vapor deposition method at a vacuum degree of 5.0×10−5 Pa or less. Firstly, HATCN was formed to a thickness of 10 nm on ITO, and thereon TrisPCz was formed to a thickness of 30 nm. mCBP, PXZ-TRZ, TBRb, and DBP were then vapor-co-deposited from separate vapor deposition sources to form a layer having a thickness of 15 nm, which was designated as a light emitting layer. At this time, the concentration of PXZ-TRZ was selected from a range of from 10% by weight, the concentration of TBRb was 3.0% by weight, and the concentration of DBP was 1.0% by weight. T2T was then formed to a thickness of 10 nm, and thereon BPyTP2 was formed to a thickness of 55 nm. Lithium fluoride (LiF) was then vacuum vapor-deposited to a thickness of 0.8 nm, and then aluminum (Al) was vapor-deposited to a thickness of 100 nm to form a cathode, thereby producing an organic electroluminescent device.
Production and Evaluation of Organic Electroluminescent Device using CBP (First Organic Confound), ptris-PXZ-TRZ (Second Organic Compound), and DBP (Third Organic Compound)
In this example, an organic electroluminescent device was produced and evaluated by using CBP shown below as the first organic compound, ptris-PXZ-TRZ shown below as the second organic compound, and DBP as the third organic compound. CBP has a lowest singlet excitation energy level ES1 of 3.26 eV and a lowest triplet excitation energy level ET1 of 2.55 eV, and ptris-PXZ-TRZ has a lowest singlet excitation energy level ES1 of 2.30 eV and a lowest triplet excitation energy level ET1 of 2.16 eV.
Thin films were laminated on a glass substrate having formed thereon an anode formed of indium tin oxide (ITO) having a thickness of 110 nm in the same manner as in Example 1.
Firstly, α-NPD was formed to a thickness of 35 nm on ITO, and thereon CBP, ptris-PXZ-TRZ, and DBP were vapor-co-deposited from separate vapor deposition sources to form a layer having a thickness of 15 nm, which was designated as a light entitling layer. At this time, the concentration of ptris-PXZ-TRZ was 15% by weight, and the concentration of DBP was 1% by weight. TPBi was then formed to a thickness of 65 nm, lithium fluoride (LiF) was vacuum vapor-deposited thereon to a thickness of 0.8 nm, and then aluminum (Al) was vapor-deposited to a thickness of 100 nm to form a cathode, thereby producing an organic electroluminescent device.
The organic electroluminescent device thus produced was measured for light emission spectra with a luminance set at 10 cm/m2, 100 cm/m2, 500 cm/m2, and 1,000 cm/m2. The results are shown in
Production and Evaluation of Organic Electroluminescent Device using DPEPO (First Organic Compound), ASAQ (Second Organic Compound), and TBPe (Third Organic Compound)
In this example, an organic electroluminescent device was produced and evaluated by using DPEPO shown below as the first organic compound, ASAQ shown below as the second organic compound, and TBPe shown below as the third organic compound. DPEPO has a lowest singlet excitation energy level ES1 of 3.20 eV and a lowest triplet excitation energy level ET1 of 3.00 eV, ASAQ has a lowest, singlet excitation energy level ES1 of 2.75 eV and a lowest triplet excitation energy level ET1 of 2.52 eV, and TBPe has a lowest singlet excitation energy level ES1 of 2.70 eV.
Thin films were laminated on a glass substrata having formed thereon an anode formed of indium tin oxide (ITO) having a thickness of 110 nm in the same manner as in Example 1.
Firstly, α-NPD was formed to a thickness of 35 nm on ITO, and thereon mCP was formed to a thickness of 10 nm. DPEPO, ASAQ, and TBPe were then vapor-co-deposited from separate vapor deposition sources to form a layer having a thickness of 15 nm, which was designated as a light emitting layer. At this time, the concentration of ASAQ was 15% by weight, and the concentration of TBPe was 1% by weight. DPEPO was then formed to a thickness of 8 nm, and thereon TPBi was formed to a thickness of 37 nm. Lithium fluoride (LiF) was vacuum vapor-deposited thereon to a thickness of 0.3 nm, and then aluminum (Al) was vapor-deposited to a thickness of 100 nm to form a cathode, thereby producing an organic electroluminescent device.
Production and Evaluation of Organic Electroluminescent Device using DPEPO (First Organic Compound), ASAQ (Second Organic Compound), and TBPe (Third Organic Compound)
An organic electroluminescent device was produced in the same manner as in Example 5 except that the thickness of TPBi was changed to 57 nm.
The energy difference ΔEst between the lowest singlet excited state and the lowest triplet excited state and the photoluminescence quantum efficiency ϕPL of the light emitting layer thus formed are shown in Table 24.
Production and Evaluation of Organic Electroluminescent Device using mCP (First Organic Compound), MN04 (Second Organic Compound), and TTPA (Third Organic Compound)
In this example, an organic electroluminescent device was produced and evaluated by using mCP shown below as the first organic compound, MN04 shown below as the second organic compound, and TTPA shown below as the third organic compound. mCP has a lowest singlet excitation energy level ES1 of 3.30 eV and a lowest triplet excitation energy level ET1 of 2.90 eV, MN04 has a lowest singlet excitation energy level ES1 of 2.60 eV and a lowest triplet excitation energy level ET1 of 2.47 eV, and TTPA has a lowest singlet excitation energy level ES1 of 2.34 eV.
Thin films were laminated on a glass substrate having formed thereon an anode formed of indium tin oxide (ITO) having a thickness of 110 nm in the same manner as in Example 1.
Firstly, TAPC was formed to a thickness of 35 nm on ITO, and thereon mCP, MN04, and TTPA were then vapor-co-deposited from separate vapor deposition sources to form a layer having a thickness of 15 nm, which was designated as a light emitting layer. At this time, the concentration of MN04 was 50% by weight, and the concentration of TTPA was 1% by weight. TPBi was then formed to a thickness of 65 nm, lithium fluoride (LiF) was vacuum vapor-deposited thereon to a thickness of 0.8 nm, and then aluminum (Al) was vapor-deposited to a thickness of 100 nm to form a cathode, thereby producing an organic electroluminescent device.
The energy difference ΔEst between the lowest singlet excited state and the lowest triplet excited state and the photo luminescence quantum efficiency ϕPL of the light emitting layer thus formed are shown in Table 24.
Production and Evaluation of Organic Electroluminescent Device using mCBP (First Organic Compound), PXZ-TRZ (Second Organic Compound), and TBRb (Third Organic Compound)
In this example, an organic electroluminescent device was produced and evaluated by using mCBP as the first organic compound, PXZ-TRZ as the second organic compound, and TBRb as the third organic compound.
Thin films were laminated on a glass substrate having formed thereon an anode formed of indium tin oxide (ITO) having a thickness of 110 nm in the same manner as in Example 1.
Firstly, TAPC was formed to a thickness of 35 nm on ITO, and thereon mCBP, PXZ-TRZ, and TBRb were then vapor-co-deposited from separate vapor deposition sources to form a layer having a thickness of 30 nm, which was designated as a light emitting layer. At this time, the concentration of PXZ-TRZ was 25% by weight, and the concentration of TBRb was by weight. T2T was then formed to a thickness of 10 nm, and thereon Alq3 was formed to a thickness of 55 nm. Lithium fluoride (LiF) was vacuum vapor-deposited thereon to a thickness of 0.8 nm, and then aluminum (Al) was vapor-deposited to a thickness of 100 nm to form a cathode, thereby producing an organic electroluminescent device.
The energy difference ΔEst between the lowest singlet excited state and the lowest triplet excited state and the photoluminescence quantum efficiency ϕPL of the light emitting layer thus formed are shown in Table 24.
Production and Evaluation of Organic Electroluminescent Device using CBP (First Organic Compound), ptris-PXZ-TRZ (Second Organic Compound), and DBP (Third Organic Compound)
In this example, an organic electroluminescent device was produced and evaluated by using CBP as the first organic compound, ptris-PXZ-TRZ as the second organic compound, and DBP as the third organic compound.
Thin films were laminated on a glass substrate having formed thereon an anode formed of indium tin oxide (ITO) having a thickness of 110 nm in the same manner as in Example 1.
Firstly, TAPC was formed to a thickness of 35 nm on ITO, and thereon CBP, ptris-PXZ-TRZ, and DBP were then vapor-co-deposited from separate vapor deposition sources to form a layer having a thickness of 15 nm, which was designated as a light emitting layer. At this time, the concentration of ptris-PXZ-TRZ was 15% by weight, and the concentration of DBP was 1% by weight. TPBi was then formed to a thickness of 65 nm, lithium fluoride (LiF) was vacuum vapor-deposited thereon to a thickness of 0.8 nm, and then aluminum (AI) was vapor-deposited to a thickness of 100 nm to form a cathode, thereby producing an organic electroluminescent device.
The energy difference ΔEst between the lowest singlet excited state and the lowest triplet excited state and the photoluminescence quantum efficiency ϕPL of the light emitting layer thus formed are shown in Table 24.
As shown in Table 25, all the organic electroluminescent devices of Examples 6 to 9 had a high current efficiency and a high power efficiency and achieved a high external quantum efficiency of 11% or more.
The organic electroluminescent device of the invention provides a high light emission efficiency, and thus may be applied as an image display device to various equipments. Accordingly, the invention has a high industrial applicability.
1 substrate
2 anode
3 hole Injection layer
4 hole transporting layer
5 light emitting layer
6 electron transporting layer
7 cathode
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-168587 | Aug 2013 | JP | national |
| 2014-038472 | Feb 2014 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17071719 | Oct 2020 | US |
| Child | 17809786 | US | |
| Parent | 14911761 | Feb 2016 | US |
| Child | 17071719 | US |
